Removing secretions from the lungs of a medical patient has presented problems for a long time. This is particularly true of secretion removal from an infant. As described in U.S. Pat. No. 4,838,255, respiratory distress frequently occurs in infants and small children experiencing respiratory problems. This is commonplace in premature infants. When an infant or small child is unable to breathe adequately on its own, intubation and involuntary ventilation is provided via an endotracheal tube. This requires periodic, involuntary removal, via a small suction or aspirating catheter tube, of secretions which accumulate in the lungs. Catheter insertion should be accurately accomplished without injury to or penetration of the lungs by the catheter tube. Percise control in placement of the suction catheter tube is of great concern because of the risk of trauma, injury and death as a result of placement.
Known patents concerning catheter insertion are U.S. Pat. No. 4,838,255 (mentioned above) and U.S. Pat. Nos. 3,444,860, 3,894,540, and 4,062,363. U.S. Pat. 4,838,255 is related to respiratory and aspirating systems for intubated patients, including infants. U.S. Pat. Nos. 3,444,860 and 3,894,540 are related to urinary catheters, and U.S. Pat. No. 4,062,363 relates generally to catheter insertion.
Apparatus and procedures currently available rely upon tactile senses and motor skills of medical technicians to accurately control aspirating catheter insertion so as to minimize trauma and risk to the patient. For example, U.S. Pat. No. 4,838,255 discloses a static insertion guide and flexible cover which allows a technician to grasp the aspirating catheter through the cover and carefully thread the catheter along the static insertion guide into a patient's lungs.
U.S. Pat. No. 3,444,860 discloses an aseptic catheter assembly with a holder introducer which is primarily meant for use in the urinary tract. A catheter assembly including a lubricated urinary catheter tube with a collection bag connected to one end and an elongated hollow, open-ended semi-rigid holder-introducer is described. An elongated tubular membrane surrounds the holder-introducer and is connected to the catheter tube on one end such that, as the tublar membrane is telescopically forced over the holder-introducer, the catheter tube is forced from the holder-introducer into an ingress site. Tactile sensing and pressure control upon an inserted catheter is not particularly sensitive.
A urinary catheter comprising a telescoping or accordianated sheath is disclosed in U.S. Pat. No. 3,894,540. The catheter tube is inserted by serially grasping the catheter tube through the sheath and manually pushing the unfolding or telescopically extending sheath and substantially rigid catheter tube toward the point of catheter tube ingress. The catheter tube proceeds outward from the sheath and threads through the ingress site. Each time the catheter tube and sheath are released, the sheath relaxibly retruns to a less extended state such that the insertion step can be repeated. This provides for continuously inserting the catheter tube while maintaining catheter sterility, but requires gripping the catheter tube through a sheath whereby the "feel" of the catheter tube is acquired through a cover.
U.S. Pat. No. 4,062,363 discloses a telescoping or accordianated sheath having urinary and tracheal purposes. In the tracheal application, significant care must be taken to assure against too much pressure being applied when delivering a catheter tube into the lungs. This, as is true of each of the other previously described art, relies upon "feel" through a secondary cover to provide the feedback impedance to inward delivery of a catheter tube. The forces generating such "feel" are the sum of the catheter delivery retarding forces comprising the catheter feed system, the impeding factors of the patient's lung tissue and channels, and the compliance of the covering sheath which, especially when the attending technician is wearing surgical gloves, may not provide adequate retarding force feedback to signal the actual conditions which impede delivery of the catheter tube into a lung.